Background <p>Factors associated with sleep bruxism (SB) in children with mixed dentition remain incompletely understood. This study examined the relationship between sleep bruxism and sleep behaviors, oral habits, temporomandibular disorders (TMD), and health status in Turkish schoolchildren during the mixed dentition stage.</p> Methods <p>In this cross-sectional study, a representative sample of 452 schoolchildren was assessed. Sleep bruxism was assessed by a subjective-based assessment (parental report of tooth grinding during sleep). During the clinical oral examination, tooth wear, free-way space, maximum mouth opening, and signs of TMD were recorded. Parents or caregivers completed a questionnaire on sociodemographic factors, general health, sleep behavior, oral habits, and recent life changes. Associations were analyzed using the χ² or Fisher’s exact test, the Mann–Whitney U test, and logistic regression, with effect sizes (Cramér’s V, odds ratios, and r).</p> Results <p>Sleep bruxism was identified in 22.6% of the 452 children, with no significant difference between genders (<i>p</i> = .077). Regarding health status, SB was more common among children with allergic rhinitis (<i>p</i> &lt; .001; OR = 2.42, 95% CI 1.50–3.91). Regarding TMJ/jaw function and oral habits, SB was associated with head/jaw trauma, difficulty opening the mouth, TMJ pain, pain while chewing hard foods, biting hard foreign objects, chewing hard candies or ice, and leaning the jaw against the hand (all <i>p</i> &lt; .05). Regarding sleep-related variables, SB was associated with snoring, drooling on the pillow, bedwetting, restless sleep, and mouth-breathing (all <i>p</i> &lt; .05). Regarding family factors, SB was associated with parental and sibling grinding and with parental divorce (all <i>p</i> &lt; .05). TMD symptoms were present in 22.5% of bruxism-positive children compared with 12.3% of bruxism-negative children (<i>p</i> = .010; OR = 2.08, 95% CI 1.18–3.65); all effect sizes were small (Cramér’s V ≤ 0.21). No significant association was found between SB and tooth wear (<i>p</i> = .282). In multivariable analysis, allergic rhinitis, parental history of grinding, drooling on the pillow, restless sleep, and TMD remained independently associated with SB.</p> Conclusions <p>Sleep bruxism was associated with several sleep-related, respiratory, behavioral, and family-history factors and with TMD signs and symptoms, although all associations were of small magnitude. After multivariable adjustment, allergic rhinitis, parental history of grinding, drooling on the pillow, restless sleep, and TMD were independently associated with SB. Given the cross-sectional design, these findings indicate associations rather than causal or aetiological relationships.</p> Ethics <p>Approved by the Ethics Committee of Dokuz Eylul University (2024/13–18).</p>